There are, of course, many products available in the food industry which have an expanded structure and many processes have been devised to expand various food materials. U.S. Pat. No. 4,259,359 to Spicer describes a successful high-protein, whole wheat grain expanded food product. That product, however, contains a substantial level of fat. Current trends in snack food products and food products in general is to provide lower level of fat. The process described in the Spicer patent provides an expanded food product by grinding whole wheat having at least 11% protein to provide a ground whole wheat material which is formed into a dough. The dough has an edible acid present and may have a low level of fat present in the dough. The dough is worked while the dough is subjected to heating under high temperature, short time heating conditions. The heated dough is then extruded from a high pressure zone to a low pressure zone to effect expansion of the dough. The expanded dough is then dried to provide an expanded food product of desired structure.
The process of the Spicer patent also includes a method for coating the dried, expanded wheat product with a flavoring material. In the coating process, the dried, expanded wheat product is sprayed with a liquid vegetable oil at a level of 5% by weight of the product. Thereafter, a flavor carrying oil, which is a mixture of 50% high stability liquid vegetable oil and 50% hydrogenated coconut oil is heated and a flavoring material such as cheese powder is added to the heated oil. The cheese flavored-fat combination is then applied to the pre-coated expanded wheat product at a level of 15% to provide a flavored, expanded wheat product. The coating process described in the Spicer patent is not capable of producing a flavored, expanded wheat product having less than about 15% fat. At the lower levels of fat, the flavoring components do not properly adhere to the exterior surface of the expanded wheat product.
U.S. Pat. No. 4,438,146 to Colby, et al. also describes a method for producing a cooked, edible product prepared from wheat which is in an expanded form. The Colby, et al. patent is directed to a method for producing the expanded wheat product by extruding a wheat dough through a dye at a rate sufficient to generate heat and steam in the dough without any external heat source being provided to the dye. The heating is sufficient to cook the dough in the dye to condition the wheat and the dough is extruded into a lower pressure zone to flash steam and expand the dough.
In the method of the present invention for providing an expanded wheat product with lower fat level, either the method of the Spicer patent or the Colby, et al. patent can be used to provide an expanded wheat product which is subsequently dried. The present invention, however, provides dough compositions and coating compositions and a method for coating the expanded wheat product which can be utilized to provide an expanded wheat product with substantially lower levels of fat than have heretofore been possible.
Accordingly, it is a principal object of the present invention to provide an improved method for manufacture of an expanded food product from wheat which is tender and crisp and which has a low level of fat and acceptable flavor retention properties.
It is another object of the invention to provide a method for the preparation of a wheat product wherein dough primarily comprising ground wheat, moisture and a surfactant is mixed at ambient temperature and is extruded to provide an expanded wheat product which is dried and is a coated in a two-step coating process with a reduced level of fat and a desirable level of flavoring material. These and other objects of the invention will be more particularly described in the following detailed description.